Edited by Javad Hashemi and Jeff Sammons
Dr. Micah Green, an assistant professor of chemical engineering, recently received a $360,000 grant as a part of the Air Force's Young Investigator Research Program (YIP). The Air Force Office of Scientific Research (AFOSR) awarded approximately $16.5 million in grants to 43 scientists and engineers who submitted winning research proposals.
The YIP is open to scientists and engineers at research institutions across the United States who received Ph.D. or equivalent degrees in the last five years and show exceptional ability and promise for conducting basic research.
Green’s grant is for his research on interfacial engineering for low-density graphene nanocomposites and fluids.
In November 2009, Green was recognized in envision Snaphots for developments as a part of a Rice University-led team that developed processes to completely disperse carbon nanotubes.
The experience that Green gained on carbon nanotubes in his previous research was instrumental in securing the AFOSR YIP grant in graphene research.
Graphene is similar to carbon nanotubes in many ways. Physically, carbon nanotubes are essentially graphene sheets rolled into a tubelike shape rather than a flat sheet. The properties of both carbon nanotubes and graphene sheets make these items very desirable for materials scientists. Both have outstanding mechanical, thermal, and electrical properties, as well as unusual quantum properties. Graphene is less expensive to produce, however, because it can potentially be produced from inexpensive graphite.
In the past, it was difficult for scientists to isolate individual graphene sheets because graphene sheets strongly adhere to one another. These sheets are found naturally in graphite, as graphite is a collection of many layers of graphene.
In the last few years, scientists have employed techniques that functionalize graphite by bonding oxygen and COOH groups. These techniques isolate individual sheets of graphene successfully, but often diminish their desirable properties, particularly the electronic properties.
Green’s research attempts to produce non-functionalized, pristine graphene sheets through new methods. He is developing numerous liquid-phase techniques that do not involve functionalization or covalent bonds so that the graphene properties are maintained; his techniques include the use of surfactants, wrapping polymers, and in-situ polymerization. In some cases, he and his team will use surfactants to separate the sheets, and then apply an interfacial polymer coating to stabilize the sheet. This coating, when applied strategically, can have minimal effects on desired graphene properties and can be used to prepare graphene nanocomposites with excellent dispersion and reinforcement.
The AFOSR is looking for specific properties in lightweight composites or materials, and Green will customize his methods to provide the materials at the specifications that are required. Eventually, Green will help to produce materials such as graphene-based composites, thermal fluids, and carbon fibers. These materials, through the nature of graphene, will have low-densities and low weight, all while maintaining high strength and durability.